I spent a ton of time researching decks when we built the deck on our lake house. Take a look at some of the pics in this link. I think two things apply.

Think about using hog fence as railing. I think it turns out great, from such a cheap material. I think $50 for 16 foot.

Second on the spacing, take a look closely at how my boards were laid. They have no nail/screws showing. We used a $30 tool, that grabs the board, and helps you to place a screw in at a diagonal. This tool is designed for manufactured wood, but we used on treated pine, and it was great. It puts the right amount of space between boards, and completely hides the screws. I was a little worried after shrinking the space would be too big, but after a year, it's fine.